ables, have been based on dubious assumptions. The most common, of course, is to assume that rapid population growth leads to a decline in economic growth which in turn leads to political violence, political instability, insurrectionary movements, or communism. Population growth need not be accompanied by a low rate of economic growth (the reverse was the pattern in many European countries in the 19th century and, more recently, in Hong Kong, Taiwan, South Korea, Malaya, Singapore, and Israel), nor are the most violent areas of the world those with particularly low rates of economic growth. The attempts by Ted Gurr, Harry Eckstein, and other political scientists to find explanations for violence and political instability have led to a much more complex model of interrelated variables than a simple mix of income growth and population growth (29). Moreover, there is strong evidence to support de Tocqueville's familiar argument that periods of economic growth, rather than periods of economic stagnation, are often times of political instability.
Third, in analyzing the political effects of specific demographic changes, it is important to know how these changes are perceived. It is not enough to know, for example, that different religious or racial groups are increasing their number at different rates; we must also know how each of these groups views the change in its relative size. Differential fertility rates among Methodists and Episcopalians may not be perceived as a matter of great importance in the United States, but the differential fertility rates between Catholics and non-Catholics and between whites and nonwhites are seen as matters of great political significance. The beliefs people have as to the effects of real, and sometimes imagined, demographic changes are in themselves of great political importance. For example, the rapid population growth of "coloured" peoples in Britain (partly due to the fact that a large proportion of nonwhite women are currently in the childbearing age) has led some Englishmen to fear that the character of British life would be changed in an undesirable way and, therefore, to believe that restrictive immigration policies should be pursued. Similarly, beliefs concerning the relationship between population size and national power have affected population policies in New Zealand and Australia, although changes in military technology have made such a relationship much less significant than in the past.
Sometimes a change in government policy can affect popular attitudes toward some long-familiar demographic facts. For example, illegitimacy among the poor, as such, was largely ignored by taxpayers until government took on the responsibility of providing aid to dependent children. What was once viewed benignly as simply a way of life among the lower classes has now become an irritant to many middle class Americans.
Demographers, like economists, have been accustomed to working with "hard" data. They often distinguish themselves professionally from other social scientists, such as anthropologists and political scientists, who work